In role tailored client, search for Job queue entries, In the list of job queues check if you have created any new jobs to automatically run everyday and verify the no. of minutes b/w run in Recurrence tab. Usually this value should be zero if you are running job once a day.

I'm not telling this is the exact issue you're facing but may be this can also be one of the reason for freeze.

That should be there in NAV client check once again, In your NAV client go to,
Departments/Administration/Application Setup/Job Queue/Job Queue Entries".

If you do not find there also means probably developer has customized it.

As per my knowledge usually NAV faces this issue because of high consumption of job queues. If not some bad code is written in the object you're trying to run which might be causing an infinite looping there by consuming entire memory.

Ok I will share your comment with the developer here hoping they can find something. For info, we just did a migration from 4.0 to 2016 following the upgrade steps of courses. Perhaps if you could give us some guidelines what we can trigger to look for those infinite looping what would be good for us.

If some of the setup's have changed in NAV 2016 you can just verify those setup's if i.e causing the reason for high consumption of memory. Few important things to focus,

Use background posting in most cases if it is possible to do so.

Run the “Adjust Cost-Item Entries” batch job to ensure that the inventory cost data in the customer’s database is up to date after doing the upgradation from 4.0 to 16, verify the values whether 2016 has values same as in NAV 4.0

If your organization posts inventory costs to the Microsoft Dynamics NAV general ledger, run the “Post Inventory Cost to G/L” batch job and verify the values whether the values of NAV4.0 is resembled same in 2016

This verifies that you've done your upgradation perfectly.

After that some more things to focus.
Update on posting should be unchecked in Sales Analysis View Card, check the setup of Inventory Setup for Automatic Cost Adjustment, Apart from this sometimes it might be NAV Cumulative update issue also.